Re: "make check-acceptance" takes way too long

[Thomas Huth]

On 02/08/2021 15.04, Daniel P. Berrangé wrote:
> On Mon, Aug 02, 2021 at 02:00:19PM +0100, Peter Maydell wrote:
> > On Mon, 2 Aug 2021 at 13:57, Alex Bennée <alex.bennee@linaro.org> wrote:
> > > Daniel P. Berrangé <berrange@redhat.com> writes:
> > >
> > > > On Fri, Jul 30, 2021 at 04:12:27PM +0100, Peter Maydell wrote:
> > > > > "make check-acceptance" takes way way too long. I just did a run
> > > > > on an arm-and-aarch64-targets-only debug build and it took over
> > > > > half an hour, and this despite it skipping or cancelling 26 out
> > > > > of 58 tests!
> > > > >
> > > > > I think that ~10 minutes runtime is reasonable. 30 is not;
> > > > > ideally no individual test would take more than a minute or so.
> > > > >
> > > > > Output saying where the time went. The first two tests take
> > > > > more than 10 minutes *each*. I think a good start would be to find
> > > > > a way of testing what they're testing that is less heavyweight.
> > > >
> > > > While there is certainly value in testing with a real world "full" guest
> > > > OS, I think it is overkill as the default setup. I reckon we would get
> > > > 80-90% of the value, by making our own test image repo, containing minimal
> > > > kernel builds for each machine/target combo we need, together with a tiny
> > > > initrd containing busybox.
> > >
> > > Also another minor wrinkle for this test is because we are booting via
> > > firmware we need a proper disk image with bootloader and the rest of it
> > > which involves more faff than a simple kernel+initrd (which is my goto
> > > format for the local zoo of testing images I have).
> >
> > If you look at the log which has timestamps for the output, UEFI
> > takes some extra time but it's not too awful. The real timesink is
> > when it gets into userspace and systemd starts everything including
> > the kitchen sink.
>
> Is it possible to pass "s" kernel arg to systemd to tell it to boot in
> single user mode so it skips most of userspace, while still providing
> a useful test scenario in much less time ?

FWIW, we're doing something similar in 
tests/acceptance/machine_s390_ccw_virtio.py already: The Debian job is using 
"BOOT_DEBUG=3" to drop into a debug shell early where we can already do all 
the necessary tests, and the Fedora-based job is doing the same with 
"rd.rescue". Additionally the Fedora job is also decompressing its initrd on 
the host already which is way faster than doing that via TCG in the guest. 
Both tricks saved us a significant amount of time in these jobs.

 Thomas